Electrodeposition of nickel

ABSTRACT

AN AQUEOUS ACIDIC BATH SOLUTION FOR ELECTROPLATING NICKEL INCLUDES AT LEAST ONE NICKEL SALT AS A SOURCE OF NICKEL AND, AS A BRIGHTENER, A COMBINATION OF A SULFOLENE COMPOUND AND A WATER-SOLUBLE ALLYL SULFONATE IN AN AMOUNT SUFFICIENT TO PRODUCE A BRIGHT NICKEL ELECTRODEPOSIT.

United States Patent 3,697,392 ELECTRODEPOSITION 0F NICKEL Joseph R. Duchene, Southfield, Mich., assignor to Allied Research Products, Inc., Baltimore, Md. No Drawing. Filed July 2, 1970, Ser. No. 52,083 Int. Cl. C23b 5/08 US. Cl. 204-49 4 Claims ABSTRACT OF THE DISCLOSURE An aqueous acidic bath solution for electroplating nickel includes at least one nickel salt as a source of nickel and, as a brightener, a combination of a sulfolene compound and a water-soluble allyl sulfonate in an amount sufiicient to produce a bright nickel electrodeposit.

This invention relates to'the electrodeposition of nickel and more particularly to electroplating solutions adapted to produce full bright nickel deposits. The bright nickel deposit produced according to this invention exhibits improved ductility and throwing or covering characteristics and thus is capable of improved coverage of imperfections in the base metal.

It has now been found that improved full bright, ductile nickel deposits can be obtained using an aqueous acidic nickel plating bath having incorporated therein a brightening system comprising a combination of a sulfolene compound and a water-soluble allyl sulfonate.

It has been known to modify nickel electroplating baths with brightening agents as well as with agents to improve leveling effects. The use of nickel plating baths containing a sulfolene compound, such as sulfolanyl other as a brightening agent is disclosed for instance in U.S. Pat. 3,376,207. It has been found however that in order to obtain a full bright nickel deposit to the degree desired, the said sulfolene compounds of this reference, for instance, hydroxy butyne sulfolanyl ether, had to be modified by the addition thereto of nitrogen or a nitrogen type brightener, such as an imidizol, and an aromatic carrier such as sodium saccharin or 1,3,6-naphthalene trisulfonic acid, sodium salt to obtain a full bright nickel deposit. However, the addition of these materials often produced deleterious effects with respect to the ductility and hardness of the subsequentnickel deposit. The breakdown products of nitrogen bearing compounds can be particularly deleterious, causing stresses in the subsequent nickel deposit. Accordingly, where ductility and hardness are desirable or the necessary characteristics, the use of such combinations of materials in the plating bath did not appear advisable.

It has now been found that such disadvantages can be overcome by including in the aqueous acidic nickel plating bath a brightening agent consisting essentially of a sulfolene compound in combination with a water-soluble allyl sulfonate. It has also been found that this combination of materials, i.e. the sulfolene compound and the water-soluble allyl sulfonate exhibit a synergistic effect and that this combination produces superior nickel electrodeposits when compared, for instance, to the prior art additives. Additionally, it has been found that the novel plating baths of this invention provide the desired results in the absence of any conventional nitrogen containing compounds and any aromatic sulfur compounds.

The preferred combination of materials employed in the present invention is hydroxy butyne sulfolanylether and sodium allyl sulfonate, although, as the sulfolene Fee compound the following materials can also be usefully employed: propargyl sulfolanylether, Z-butyne disulfolanylether, methyl sulfolanylether, ethyl sulfolanylether, hydroxyethylene sulfolanylether, butyl sulfolanylether, propyl sulfolanylether, hydroxybutylene sulfolanylether, vinyl sulfolanylether, l-propenyl sulfolanylether, 2-propenyl sulfolanylether, isopropenyl sulfolanylether, l-butenyl sulfolanylether, Z-butenyl sulfolanylether, hydroxybutenyl sulfolanylether, l-butynyl sulfolanylether, 2-butynyl sulfolanylether, l-pentynyl sulfolanylether, sodium sulfonate sulfolanylether, sodium ethylenesulfonate sulfolanylether.

The novel brightening agent of this invention is generally used in the amounts between 1.5 to 5 grams of sodium allyl sulfonate per liter of bath solution and 0.01 to 1.0 gram of the sulfolene compound per liter of bath solution.

In general, the process of this invention involves operating a bath at conventional nickel plating temperatures ranging from about room to boiling though usually most convenient temperatures of operation are from about F. to 170 F. The best pH values for the bath range from about 3.5 to 4.5 though a pH as low as 2 and as high as 6 can also be employed. Preferably, the pH will range between 3.0 and 5.0 in the majority of the cases. The cathodic current densities to be used average generally from about 1 to 200 amp/sq. ft. depending, for instance, on the temperature, degree of solution agitation and the composition of the bath. Higher temperatures and more rapid agitation permit higher current densities to be used effectively.

Baths for electroplating in accordance with this invention contain at least one nickel salt as a source of nickel and include well-known Watts-type bath and high chloride type bath. The Watts bath solution typically comprises around 200-400 grams/ liter of nickel sulfate, 30-75 grams/liter of nickel chloride and 30-50 grams/liter of boric acid. A high chloride type bath can contain about -300 grams/liter of nickel chloride, 40-150 rams/ liter of nickel sulfate and 30-50 grams/liter of boric acid. Considerable latitude is also permissible in respect to the types and concentrations of the nickel salts employed. For instance, as the source of nickel, nickel sulfamate as well as a combination of nickel fiuoborate with nickel sulfate and nickel chloride or a combination of nickel fluoborate with nickel chloride can be employed.

Additionally, the bath can include other brighteners, however, such other brighteners are not necessary to obtain the full bright, ductile nickel deposits of this invention. Examples of other brighteners which can be used in addition to the novel brighteners of this invention include aliphatic sulfur compounds such as methallyl sulfonate, 2-butene, l-chloro, 4-sulfonate and Z-butene, 1,4- disulfonic acid. Generally, when used, such aliphatic sulfur compounds can be present in amounts ranging from 0.1 to 10 grams/liter of solution.

Additionally, water-soluble acetylenic compounds can also be effectively included in the bath solution of this invention. The acetylenic compounds include Z-butyne- 1, 4-diol, 4-methoxy-2-butyn-1-ol, 3-hexyne-2, S-diol, 3- pentyn-l-ol, 2,4-hexadiyne-l, 6-diol. Conveniently, the water-soluble acetylenic compound can be employed in amounts ranging from about 0.01 to 0.3 grams/liter of solution.

For the purpose of giving those skilled in the art a better understanding of the invention, the following illustrative examples are given in which the aqueous acidic nickel-containing bath was made up with specified components. Electrodeposition was carried out by passing electric current through an electric circuit comprising an anode and a sheet metal or rod cathode, both immersed in the bath. The bath was agitated, usually by moving the cathode although, in certain instances, air agitation or other mechanical or electrical agitation means can be employed.

In the examples, the below described standard Wattstype bath was used as a base solution and a standard 26-7 ml. hull cell was used as the plating cell:

Nickel sulfate, oz./gal. 40 Nickel chloride, oz./ gal. 8 Boric acid, oz./gal. 6 pH 4.0-4.2 Temperature, F. 140 Current, amperes 2 Time, min. Agitation, strokes/min. 40-50 To illustrate the synergistic effect of the combination of sulfolene compound and water-soluble allyl sulfonate, Examples 1-3 below are provided.

Steel panels, nickel plated with the respective baths defined above, exhibited, only in the case where both a sulfolene compound and a water-soluble allyl sulfonate were used, i.e. Example 3, a full bright, level and ductile electrodeposit over the whole current density range. The electrodeposits resulting from both Examples 1 and 2 were significantly inferior with respect, for instance, to the brightening characteristics achieved with the brightening agent employed in Example 3.

Examples 4-6 and 8-9 illustrate that the advantages of the present invention also are not achieved when the ingredients making up the combination of materials of this invention are used, singly or in combination, with conventionally employed nitrogen bearing or aromatic sulfur containing brightening agents or when these conventional brightening agents are employed alone. Examples 4-6 and 8-10 when compared to Example 7 or Example 3 which employ the brightening agent of this invention, fail to provide the advantages attained by the present invention.

Examples 11-18 are provided to illustrate the use of sulfolene compounds other than hydroxy butyne sulfolanylether in combination with sodium allyl sulfonate and to illustrate varying proportions of each while still achieving the desired results of the present invention.

EXAMPLE 11 Hydroxy butyne sulfolauylether 0.05

, Sodium allyl sulfonate 1.5

EXAMPLE 12 Propargyl sulfolanylether 0.03

Sodium allyl sulfonate 1.5

EXAMPLE 13 2-butyne disulfolanylether 0.05

Sodium allyl sulfonate 3.

EXAMPLE 14 Ethane sulfonate sulfolanylether 0.1

Sodium allyl sulfonate 3 EXAMPLE 15 Hydroxy butyne sufolanylether 0.01

Sodium allyl sulfonate 1.5

EXAMPLE l6 Hydroxy butyne sulfolanylether 0.01

Sodium allyl sulfonate 5 EXAMPLE 17 Hydroxy butyne sulfolanylether 1 Sodium allyl sulfonate 1.5

EXAMPLE 18 Hydroxy butyne sulfolanylether 1 Sodium allyl sulfonate 5 EXAMPLE/4 G./l. Saccharin 1 EXAMPLE 5 Hydroxy butyne sulfolanylether 0.05 Salccharin 1 EXAMPLE 6 Sodium allyl sulfonate 3 Saccharin 1 EXAMPLE 7 Hydroxy butyne sulfolanylether 0.05 Sodium allyl sulfonate 3 Saccharin 1 EXAMPLE 8 1,3,6-naphthalene trisulfonic acid, sodium salt 4 EXAMPLE 9 1,3,6-naphthalene trisulfonic acid, sodium salt 4 Hydroxy butyne sulfolanylether 0.05

Unless otherwise specified, all parts and percentages in the specification and claims are by weight. The foregoing examples illustrate specific baths and processes,

several being preferred. it is to be understood that the compositions and conditions can be varied. For instance, other aqueous acidic bath solutions can be used. in place of the Watts-type bath mentioned above. For example, substantially equally favorable results can be attained using a virgin sulfamate nickel bath instead of the Watts bath specified above.

What is claimed is:

1. An aqueous acidic electroplating bath solution for producing a bright nickel deposit comprising at least one nickel salt as a source of. nickel and, as a brightener,

a combination consisting essentially of a sulfolene compound and a water-soluble allyl sulfonate in amounts suificient to produce a bright nickel deposit, said sulfolene compound being present in amounts of 0.01 to 1.0 g./l. and said water-soluble allyl sulfonate being present in amounts of 1.5 to 5 g./l. of said bath solution.

2. The electroplating bath of claim 1 wherein the sulfolene compound is selected from the group consisting of sulfolanylether, propargyl sulfolanylether, ethane sulfonate sulfolanylether and 2-butyne disulfolanylether, and the water-soluble allyl sulfonate is sodium allyl sulfonate.

3. The electroplating bath of claim .1 wherein the sulfolene compound is hydroxy butyne sulfolanylether and the water-soluble allyl sulfonate is sodium allyl sulfonate.

4. The electroplating bath of claim 3 wherein the hydroxy butyne sulfolanylether is present in an amount of 5 6 about 0.05 g./l. and the sodium allyl sulfonate is present 3,376,207 4/1968 Ericson 204-49 in an amount of about 3 g./l. 3,399,123 8/1968 Passal 204-49 3,413,295 11/1968 Passal et a1 20449 References Cited F. C. EDMUNDSON, Primary Examiner UNITED STATES PATENTS 5 2,550,449 4/1951 Brown 204-49 3,334,032 8/1967 Kardos 204-49 204DIG-2 

